‘The revolution is underway.‘
This is not the first time we’ve heard about Lithium-Sulphur battery technology. As a promising way to increase the range of EVs, but this time the claims are being made by a company that specializes EVs and EV-related tech, with a good track record – the claims are believable.
Announcement by Brighsun Group, Australia :
- Announced working on Lithium-Sulphur batteries
- Theoretical range of close to 2,000 km (1,200 miles) on a single charge
- Claims these batteries have 5 – 8 times the storage capacity of conventional rechargeable batteries (although it’s not clear what these conventional batteries that they’re referring to are)
- Another claim: new Li-S batteries can retain 91 percent of their capacity after 1,700 cycles of fast charging at a rate of 2C (being fully charged and discharged in 30 minutes).
- It adds that these batteries can still hold 74 percent of their initial capacity even after 1,000 cycles at 5C (fully charged to fully empty in 12.5 minutes)
Lithium Sulphur Battery Technology :
- Energy density: 500 wh/kg
- Use solid lithium as anodes and liquid organic electrolytes
- Operate at temperatures above lithium melting point, at 180.5ºC
- These batteries, using sulfur or selenium, avoid the growth of lithium dendrites and have high Coulombic efficiency and cycling stability.
- Li-Ion batteries are reaching their practical specific energy limit.
Li-S is one of the most promising technologies to be used in batteries for EV.
Li-S technology has higher theoretical specific energy than Li-Ion.
Li-S is cheaper and less pollutant than Li-Ion.
More about Li-S batteries :
For the layperson, how is it potentially possible for lithium-sulfur used in batteries to have six times the energy for a given weight?
In a Li-ion battery, Li+ ions shuttle between the positive electrode intercalation host (theoretical capacity as high as 280 mAh g-1) where they are stored upon discharge; and the graphitic carbon negative electrode, where they are stored on charging to a maximum content of Li0.16C (The 1 to 6 ratio means the capacity is not that great – theoretical capacity is 370 mAh g-1). Cell voltages are in the range of 3.4–3.8 V versus Li/Li+. Theoretical energy densities are around 500 Wh Kg-1on the basis of electrode materials.
The redox reaction-based storage mechanism in Li-S system is fundamentally different from the intercalation process of lithium-ion battery. The theoretical capacity of sulfur (positive electrode) is 1675 mAh g-1, thanks to the formation of Li2S when sulfur combines with lithium (negative electrode). The 2 to 1 ratio clears the holds-a-lot-of-lithium hurdle and promises a wonderful match for the ultra-high capacity lithium anode (3860 mAh g-1). The theoretical energy density of the Li-S system is then determined by the theoretical capacity of sulfur (1675 mAh g-1) and its potential of 2.15 V versus Li/Li+, to be around 2,500 Wh kg–1.
Although lithium-sulfur offers up to a five-fold increase in gravimetric energy density compared to Lithium-ion, from a practical point of view, and considering the breakthrough of our research group and the advancements of other research institutions and companies, you can expect to see around a two-fold increase at the battery pack level when first introduced to the market.
Case study: Oxisenergy
Oxis Cell and battery technology advantages :
The key components
- A Lithium Metal anode
- A Sulfur-based cathode
- A safe electrolyte protecting the lithium metal
- A state of the art separator
The key strengths
- Full discharge
- Cycle life
- Cost effectiveness
- Pressure tolerance
- Maintenance free
Li-S production cost projections are significantly lower than Li-Ion due to lower raw material cost (i.e. Sulfur) and high energy density (less material required for same energy). This cost advantage is expected to be a key driver for widespread adoption of Li-S technology.